Semiconductor device and method of fabricating the same

Abstract

A semiconductor device having interconnects is reduced in leakage current between the interconnects and improved in the TDDB characteristic. It includes an insulating interlayer 108, and interconnects 160 filled in grooves formed in the insulating interlayer, including a copper layer 124 mainly composed of copper, having the thickness smaller than the depth of the grooves, and a low-expansion metal layer 140, which is a metal layer having a heat expansion coefficient smaller than that of the copper layer, formed on the copper layer.

Description

[0001]This application is based on Japanese patent application No. 2004-053620 the content of which is incorporated hereinto by reference.DISCLOSURE OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a semiconductor device having interconnects, and a method of fabricating the same.[0004]2. Related Art[0005]Conventional semiconductor device uses interconnects configured by forming interconnect-forming grooves in an insulating interlayer, and by filling the interconnect-forming grooves with a metal layer such as a copper (Cu) layer (see Japanese Laid-Open Patent Publication No. 2001-176965, for exapmle).[0006]FIG. 11 is a sectional structural view of an exemplary configuration of a conventional semiconductor device.[0007]As shown in FIG. 11, the semiconductor device has semiconductor elements such as transistors, resistors, capacitors and so forth, all of which not shown, formed on a semiconductor substrate 100, and thereon a stopper insulating layer...

AI Technical Summary

Benefits of technology

[0020]In the present invention, the metal layer formed on the copper layer successfully suppresses stretching and shrinkage of the copper layer, and also prevents the copper diffusion. Because the copper layer has the thickness smaller than that of the insulating interlayer, the upper surface of the copper layer and the upper surface of the insulating interlayer reside at different levels of height, and this successfully prevents copper from diffusing from the upper surface of the copper layer via the upper surface of the insulating interlayer during operation of the semiconductor device. This contributes reduction in the leakage current as compared with the conventional technique.

[0035]The metal layer has a heat expansion coefficient smaller than that of the copper layer, so that the metal layer shows smaller stretching or shrinkage than the copper layer shows during the fabrication process. This is successful in preventing the barrier metal layer from cracking due to the stretching and shrinkage of the copper layer, and in preventing copper ion from drifting via the crack into the insulating layer.

Problems solved by technology

Under accelerating trends in micronization of the semiconductor devices and concomitant narrowing of the distance between interconnects being expected for the future, even the above-described conventional configuration of the semiconductor device may result in TDDB (time-dependent dielectric breakdown) failure, due to leakage current between the interconnects applied with an electric field.

In this sort of configuration having the distance between the interconnects shorter than the previous, the electric field will be more likely to concentrate to the upper portion of the interconnects when applied with voltage, and will cause the TDDB failure.

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